Heavy crude oils are recovered by injecting steam into the reservoir and heavy crude oil emulsions are recovered at well heads. These heavy crude oil emulsions are separated into an oil phase and a water phase by employing physical and/or electrostatic phase separation techniques with the aid of chemical demulsifiers. Heavy crude oils contain about 3 to 8 wt % sulphur and are significantly heavier than conventional lighter crude oils. Thus, upgrading of the oil is required prior to utilization of these crude oil resources in existing refineries. The term "upgrading" is used herein to designate a catalytic process in which the heavy hydrocarbons and coke precursors (as measured by the Conradson carbon residue) of the heavy crude oil emulsions are converted, at least in part, to lower boiling hydrocarbon products while simultaneously decreasing the concentration of sulphur, nitrogen and metallic contaminants present in the crude oil. Upgrading includes a number of processes, such as hydrocracking, hydrogenation, desulphurization, denitrogenation and demetallation.
The theoretical principles involved in one embodiment of the present invention are the activation of water via the so-called water-gas-shift reaction (that is, the reaction of H.sub.2 O with CO to produce H.sub.2 and CO.sub.2) in the heavy crude oil emulsion to generate hydrogen in situ for upgrading purposes. These processes are effected by certain catalysts, as described in detail below. The catalysts or catalyst precursors employed herein refer to those substances which, when contacted with emulsion, produce hydrogen which reacts with heavy crude oil in the emulsion for upgrading purposes and/or which utilize hydrogen for upgrading heavy crude oil emulsion.
The water-gas-shift reaction is carried out industrially over heterogeneous catalysts comprising of metal oxides (See Newsome, D.S. Cat. Rev.-Sci. Eng., 21(2) 275-318 (1980)). Recently, homogeneous catalysts based on Group VI B and VIII B transition metal carbonyls (e.g., Mo(CO).sub.6, W(CO).sub.6, Cr(CO).sub.6, Ru.sub.3 (CO)12 and Fe(CO).sub.5) have been reported to be active for the water-gas shift reaction in aqueous alcoholic solutions. (See Laine, R. M. and Wilson, R. B., "Aspects of Homogeneous Catalysis", R. Ugo (ed), Vol. 5, p.216-240, D. Reidel Pub. Co., 1984). It is stated that polar solvents are required for the catalytic activity of these catalysts. (See Slegeir, W. A. R., Sapienza, R. S. and Easterling, B., "Catalytic Activation of Carbon Monoxide", ed. A.C.S. Symposium Series, 152, 1981, p. 325-343). However, in the present invention, we have discovered that certain metal complexes and compounds are effective for catalyzing the water-gas-shift reaction in non-polar hydrocarbon medium, as described further below.
One major reaction in the upgrading of crude oil is desulphurization. Sulphur is present in crude oil primarily in the form of organic compounds, such as thiols, sulphides, thiophenes and condensed heterocyclic compounds. Hydrodesulphurization is the removal of sulphur from hydrocarbon feedstocks by a catalytic reaction of sulphur compounds with molecular H.sub.2 to give H.sub.2 S. The commercial hydrodesulphurization processes are heterogeneously catalyzed by Co, Mo, Ni and W oxides supported on acidic oxides, such as .gamma.0 -Al.sub.2 O.sub.3 (See Vrinat, M. L. and De Mourges, L., Appl. Catal. 5, 43-57, 1983). These processes are carried out in fixed-bed, trickle, slurry and fluidized bed reactors at temperatures and pressures ranging between about 340.degree. and about 425.degree. C. and pressures of about 800 to about 2500 psia. Hydrodesulphurization of benzothiophene and dibenzothiophene in tetralin were achieved by co-feeding CO and H.sub.2 O to a trickle bed reactor. A presulphided commercial Ni-Mo/Al.sub.2 O.sub.3 was used. (See Kumar, M., Akgerman, A. and Anthony, R. G., Ind. Eng. Chem. Process Des. Dev. 23, 88-93 (1984); Hook, B. D. and Akgerman, A. Ind. Eng. Chem. Process Des. Dev. 25, 278- 284 (1986)).
U.S. Pat. No. 3,676,331 describes a method and catalysts for the upgrading of hydrocarbons which comprises introducing water and a catalyst system containing at least two components into the hydrocarbon. At least one component of the catalyst system promotes the generation of hydrogen by reacting with water and another of the components is used in upgrading reactions. U.S. Pat. Nos. 4,134,825, 4,192,735 and 4,244,839 and German O.S. 2,729,552 teach that catalysts generated in situ in the feed are effective for upgrading hydrocarbons in the presence of externally-supplied hydrogen. Canadian Patent No. 1,183,098 teaches the hydrogenation of carbonaceous material by iron carbonyl, preferably Fe.sub.2 (CO).sub.9, in the presence of hydrogen and/or a mixture of carbon monoxide and hydrogen. U.S. Pat. No. 4,325,802 teaches the processing of coal by reacting CO and H.sub.2 O with metal carbonyls or low valent complexes under alkaline conditions at sufficiently high temperatures and pressures to produce liquid hydrocarbons. However, none of the prior art refers to utilization of water present in the emulsion to achieve hydrogen generation for upgrading hydrocarbons and for emulsion breaking.